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J/A+A/477/147       X-ray sources in Westerlund 1            (Clark+, 2008)
Unveiling the X-ray point source population of the Young Massive Cluster
Westerlund 1.
    Clark J.S., Muno M.P., Negueruela I., Dougherty S.M., Crowther P.A.,
    Goodwin S.P., De Grijs R.
   <Astron. Astrophys., 477, 147-163 (2008)>
   =2008A&A...477..147C
ADC_Keywords: Clusters, open ; X-ray sources ; Photometry

Keywords: stars: evolution - X rays: stars -
          open clusters and associations: individual: Westerlund 1

Abstract:
    We investigate the nature of the X-ray point source population within
    the Young Massive Cluster Westerlund 1.

    Chandra observations of 18 ks and 42 ks were used to determine the
    X-ray properties of emitters within Wd 1, while a comprehensive
    multiwavelength dataset was employed to constrain their nature.

    We find X-ray emission from a multitude of different stellar sources
    within Wd 1, including both evolved high mass and low mass pre-MS
    stars.

Description:
    Wd 1 (l=339.5, b=-0.4) was observed with the Chandra X-ray Observatory
    Advanced CCD Spectrometer Spectroscopic array on 2005 May 22 for 18ks
    (sequence 6283) and 2005 June 20 for 42ks (sequence 5411).

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table1.dat        97      241   Catalogue of the properties of the 241 X-ray point
                            sources detected in the 2 epochs of observations
table3.dat        98       53   Summary of the X-ray and optical properties of the
                            X-ray point sources with high mass stellar
                            counterparts


See also:
         II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
          I/284 : The USNO-B1.0 Catalog (Monet+ 2003)
 J/A+AS/127/423 : VI photometry of Westerlund 1 and 2 (Piatti+ 1998)


Byte-by-byte Description of file: table1.dat

   Bytes Format Units       Label     Explanations

   1- 15  A15   ---        [CMN2008]  X-ray Identifier (HHMMSS.s+DDMMSS)
  17- 25  F9.5  deg         RAdeg     Right ascension in decimal degrees (J2000)
  27- 35  F9.5  deg         DEdeg     Declination in decimal degrees (J2000)
  37- 40  F4.1  arcmin      Offset    Angular offset from the aim point of the
                                        observation
  42- 45  F4.1  arcsec      e_Pos     Positional uncertainty
  47- 50  F4.1  ks          LiveTime  Detector live time
  52- 57  F6.1  ct          Counts    Net counts in the 0.5-8.0keV band
  59- 62  F4.1  ct          E_Counts  Error on net counts (upper limit)
  64- 67  F4.1  ct          e_Counts  Error on net counts (lower limit)
  69- 73  F5.2  ---         HR        Hardness ratio (G1)
  75- 78  F4.2  ---         E_HR      ?=- Error on hardness ratio (upper limit)
  80- 83  F4.2  ---         e_HR      ?=- Error on hardness ratio (lower limit)
  85- 89  F5.1 10-7ph/cm2/s FX        X-ray flux in the 0.5-8.0keV band
  91- 92  A2    ---         Var       [sl ] Source variability on (s)hort or
                                            (l)ong timescales
  94- 97  A4    ---         NCP       Counterpart flag (2)

Note (2): Indicates whether an X-ray source has an optical or near-IR
          counterpart. The source catalogues utilised are
      1 = Clark et al. (2005A&A...434..949C)
      2 = Piatti et al. (1998, Cat. J/A+AS/127/423
      3 = the 2MASS catalogue (Cutri et al., 2003, Cat. II/246)
      4 = the USNO-B1.0 survey (Monet et al., 2003, cat. I/284)
      Designations for optical or near-IR counterparts for sources within
      the 5'x5' field centred on Wd1 are presented in table3.dat file.


Byte-by-byte Description of file: table3.dat

   Bytes Format Units    Label     Explanations

   1- 15  A15   ---     [CMN2008]  X-ray Identifier (HHMMSS.s+DDMMSS)
      17  A1    ---   n_[CMN2008]  [i] Note on Name (1)
  18- 22  F5.1  ct       Counts    Net counts in the 0.5-8.0keV band
  24- 27  F4.1  ct       E_Counts  Error on net counts (upper limit)
  29- 32  F4.1  ct       e_Counts  Error on net counts (lower limit)
  34- 38  F5.2  ---      HR        Hardness ratio (G1)
  40- 43  F4.2  ---      E_HR      ?=- Error on Harness ratio (upper limit)
  45- 48  F4.2  ---      e_HR      ?=- Error on Harness ratio (lower limit)
  50- 51  I2    ---      Seq       ?=- Number of the source in the finding chart
                                       (Fig. 6) (2)
  53- 58  A6    ---      OptID     Optical designation (3)
  61- 64  F4.1  mag      Bmag      ?=- B magnitude
  66- 70  F5.2  mag      Vmag      ?=- V magnitude
  72- 76  F5.2  mag      Rmag      ?=- R magnitude
  78- 82  F5.2  mag      Imag      ?=- I magnitude
  84- 96  A13   ---      SpType    MK spectral type (4)
      98  A1    ---      Var       [AEP] Variability flag (5)

Note (1): i: 164706.2-455048 was found to be variable in these observations

Note (2): We strongly advise that these numbers should not form the basis
     for a new naming convention.
Note (3): Sources with 2MASS or Piatti et al. (1998, Cat. J/A+AS/127/423,
     Cl* Westerlund 1 PBC NNN in Simbad) designations are indicated.
Note (4): For those sources for which no entry is given but for which
     photometric data are available, we predict a spectral classification
     earlier than B0.5Ia (Sect. A.3).
Note (5): Stars which Bonanos (2007AJ....133.2696B) find to be as follows:
      E = Eclipsing photometric variable
      P = Periodic photometric variable
      A = Aperiodic photometric variables


Global notes:

Note (G1): HR=(H-S)(H+S) where S is the number of counts in the 0.5-2.0keV
     and H number of counts in the 2.0-8.0keV


History:
    From electronic version of the journal
(End)                                      Patricia Vannier [CDS]    15-Feb-2008